The act of double clicking the orb is analogous to double clicking the control box in a regular window (in the xamRibbonWindow and in MS Office). In both cases, the window is closed. If you really want to prevent this behavior then you will have to intercept the RibbonWindowCommands.CloseCommand (e.g. by adding a handler for the CommandManager.PreviewCanExecute event and when the e.Command is RibbonWindowCommands.CloseCommand set CanExecute to false and Handled to true).